Peters



UNITED STATES PATENT OFFICE.

MICHEL PERRET, oE PARIS, FRANCE.

FU RNACE.

SPECIFICATION forming part of Letters Patent No. 402,474, dated April 30, 1889.

Application filed November` 9, 1888. Serial No. 290,389.

(No model.) Patented in France February 17, 1887, No. 181,623; in

Denmark April 24:, 1887, No. 641; in Belgium December 28, 1887, No. 80,089, and in England December 29, 1887, No. 17, 899.

T @ZZ whom t may concern.-

Be it known that LMICHEL PERRET, man-4V which the following is a specification.

nverulent matter rolls.

.Thisv invention, relating to furnaces or fireplaces for burning pulverulent materials, consists in an improved arrangement of the supports on which the materials are burned, whereby a large area of surface is exposed to the action of the air, and the combustion is thereby accelerated, as hereinafter explained.

The combustion of pulverulent or dusty fuel upon solid surfaces in furnaces with horizontal partitions or shelves, as heretofore constructed, presents the disadvantage of involving a considerable amount of labor in drawing the fuel4 from one shelf to another and spreading it on theshelves. To obviate'this difficulty the weight of the fuel itself is utilized according to this invention for causing it to descend from ,one shelf to another; and this object is attained by means of an arrangement hereinafter described, wherein avacant or hollow space is left between the sides'of cones or heaps, down which the dusty or pul- A y slight movement or disturbance with a rake or poker is sufficient to cause the fuel to descend without effort, and the air and gases circulate about the surfaces of the heaps as in afurnace with solid shelves. In both of these systems the air acts on the surface only of the fuel, and the combustion, owing to the small extent of this surface, is not very active, and in fact it is not possible to burn with advantage more than about two kilograms of fuel per hour and per square meter of surface exposed to the air, which merely glides horizontally along this surface.

The" combustion of fragments or lumps of fuel upon a grate proceeds under entirely different conditions. The air surrounds each 'fragment or lump which presents, say six or more sides to the action of the air in the case of lumps-in the form of cubes, for exampleand about sixty kilograms of fuel per hour and per square .meter can thus be burned with facility. Moreover, the direction of the air being continually changed, in order to pass between the lumps, the gases are caused to impinge on the solid parts with a force in proportion to the speed of the gas, resulting from the contraction of the passages between the lumps. Thereaction of a gaseous body on a solid body is greatly promoted by this impact-as in a forge-fire, for example.

In order to obtain with pulverulent fuel conditions approaching as nearly as possible to those under which the solid fuel is burned on a grate, as aforesaid, it is necessary to subdivide the pulverulent matter without previous preparation. This is accomplished to a certain extent by means of the present invention, as hereinafter described.

The furnace is constructed with horizontal partitions arranged one over theother, as in a furnace with shelves, but with the important difference that the partitions are perforated in such a manner that when the combustible material is thrown onto the upper shelf or partition it falls through the holes and covers all the shelves in succession, forming underneath each opening a small heap or cone of a form corresponding to that of .the opening.

The size of the openings, their shape, and their position relatively to one another are calculated in such a manner as to leave between the heaps spaces or intervals sufficient for the passage of air. By arranging the holes in the form of a quincunx, or so that the openings between one series of heaps are placed opposite the solid parts of the next series, the air and gases are caused to impinge against the sides of the heaps of fuel. The

heaps tend to shrink or diminish in size as they burn away; but the loss is continually made'up or compensated by fresh fuel de-. scending from the shelf above, so that the action is rendered uniform and continuous so long as the supply of material is kept up.

The furnace is charged in a similar way to a furnace with ordinary or unperforated shelves; but it is sufficient to pass a rake or poker over or through the conical heaps, so as to disturb them in order to cause the fuel to pass from one shelf to another, forming heaps on each shelf automatically and with perfect regularity without the intervention of any special tool or instrument, the arrangement of the orilices being such that the holes or openings in each shelf are placed over the solid parts of the shelf next beneath it.

The lower shelf may be entirely cleared in order to maintain separate the materials on di iferent shelves-in order to obtain ashes entirely free from. combustible matter, for example. This advantage has-heretofore been obtained by means ofnfurnaces divided into separate compartments.

And in order that my said invention may be fully understood, l shall now proceed more particularly to describe the same, and for that purpose shall refer to the several figures on the annexed. sheets of drawings, the same letters of reference indicating corresponding parts in all the figures.

Figure l of the accompanying drawings represents in longitudinal vertical section a furnace constructed according to this invention. Fig. 2 represents the furnace in transverse section, and Fig. 3 in horizontal section. Fig. 4 is a diagrammatic plan showing the arrangement of the conical heaps of fuel in the furnace, Figs. l, 2, and 3. Fig. 5 is alongitudinal section of a modied form of my improved furnace. Fig. (l is a transverse scction; Fig. 7, a sectional plan of the same; and Fig. S is a diagram of the conical heaps in the furnace, Figs. 5, 6, and 7.

This furnace is constructed with walls M, of brick-work or masonry, inclosing a series of shelves or horizontal partitions, A A', and an ash-pit, B, at the lower part. The front wall is provided with openings C C C2, formed in a cast-iron plate, P, and capable of being closed by hinged doors. The fuel is introduced through the opening C and placed on the upper shelf, whence it passes tothe lower shelves in succession, the resulting ash being received in the ash-pit at the bottom.

Each shelf, with the exception of the bottom shelf, A, is perforated with openings o, through which the pulverulent fuel falls and forms upon the shelf next beneath it a corresponding number of separate heaps with sloping sides. The said openings or holes o are arranged quincuncially in each shelf, as indicated in the plan Fig. 3 of the drawings, their number, their sectional area, and the interval between them being regulated according to the nature of the combustible. In all cases they are so arranged that each openin g corresponds with a solid part on the shelf below. The effect of this arrangement is that on each shelf there are formed as many separate heaps as there are openings or holes in the shelf above, and each heap assumes a conical form.

Another result of the arrangement is that the air or gas supporting combustion is caused to circulate around the heaps on all sides and to impinge against them, and consequently to deeply penetrate the combustible material, which under these conditions burns more actively than it would do if the air simply glided over its surface. The vertical distance between the shelves is greater at the upper part and gradually diminishes toward the lower part.

According to the arrangement illustrated in Figs. l, 2, and 3, the furnace is surrounded by an outer casing, E, forming a heatingchamber, D, in the space between this Outer casing and the sides'or walls M of the furnace. The air required to support ecnibustion is introduced through and the supply is regulated by doors adapted to the openings C C C2, the air circulating from one shelf to another by passing through openings V, arranged alternately at opposite ends of the fur nace. The products of combustion escape at the upper part of the furnace through a flue or chimney, T, which conducts' them to 'the place where they are required, and the ash is withdrawn through the opening C2.

Figs. 5, G, and 7 illustrate in transverse longitudinal and horizontal section, respectively, a furnace according to this invention, in which the walls M are made as thin as possible and are lined with fire-proof or refractory slabs or tiles m, provided at the sides of the furnace with projections or ledges fn, supporting the perforated shelves A. The said walls are covered externally with a casing lcomposed of plates l), connected at the corners by angle -irons b and strengthened, where necessary, by bars of iron of suitable section. This reduction of the walls is on account of the high temperature produced in the furnace, and the continuous metal casing is employed for the purpose of preventing accidental admission of air, at the same time insuring the preservation of the apparatus, as is commonly practiced in the construction of furnaces which are provided with a metal casing with the object of supporting the sides, or in which the sides are made of metal with a refractory lining. Any suitable materials or composition may be employed to construct the thin walls, and wrought or cast iron or tiles alone or in combination may be employed to form the outer casino.

In the furnace illustrated in Figs. 5, 6, and 7, the number of the perforated shelves A is reduced to two, in consequence of the active or rapid combustion resulting from the divided condition of the materials, the cost of construction and labor in building the furnace being likewise diminished. These shelves are arranged at equal distances apart. The number of holes or openings o is not the same in both shelves, being smaller in the lower shelf than in the upper, this arrangement being necessary when the furnace is supplied IOO IIO

.approximately uniform distribution of the -material on the separate shelves, and at the same time provide sufficient space for working the materials between the shelves. 4

` At the rear of the upper shelf there is a raised part or bench, S, in which are formed openings for the escape of the products of combustion which have circulated about and `penetrated the heaps on the lower shelf. The

object of this raised part is to provide a passage for the escape of the gases that will not be liable to be choked with the fuel, which is thus prevented from falling onto the unperforated rear portion of the lower shelf.

Fig. 4 illustrates in plan the principle on which the heaps are distributed on the shelves in the furnace represented in Figs. 1, 2, and 3, and Fig. 8 similarly illustrates the arrangement of the heaps in the furnace represented in Figs. 5, 6, and 75 As indicated by these Figs. 4 and 8, (andFigs. 2 and 6,) the fuel does not present a flat horizontal surface to the action of the air and gases, as in the ordinary arrangements, but exposes aseries of inclined or conical surfaces, with the opening between the lheaps in one line of heaps arranged opposite the heaps in the next line, so as to compel the streams f air and gases to follow sinuous paths, as indicated by the arrows :rand y, and impinge against all the heaps in succession. I

The ltire may be started at any suitable point, but preferably on the bottom or one of the lower shelves, and the materials are caused to descend through the furnace by stirring the heaps with a suitable tool or hooked :instruinent, so as to cause them to fall through the openings and form heaps on the next shelf. With this object the burned materials on the bottom shelf, A, are first raked into the ash-pit, after which the heaps on the lo'west perforated shelf, A, are raked down through the perforations onto the bottom shelf, and so on, thus working upward until the top shelf is cleared, and a new charge may then be placed on this shelf. Considerable intervals of time may be allowed to pass between each charging operation, as the lower heaps are fed or supplied automatically from the upper heaps in proportion as they tend to diminish in volume owing to the oombustion. y

'In `the case of materials .that are not reduced in volume by coinbustion--such as pyrites, certain anthracites, furnace residues, irc-which produce a large volume of ash or cinder, the operation requires to be repeated more frequently, in order to induce the materials to descend. In either case the furnace with the perforated shelves possesses considerable advantages compared to a furnace with solid shelves, in which the materials, in order to pass from one shelf to another, require t0 be moved more frequently, and prolonged exertion is required for moving thelmaterial over the entire'length of each shelf in order to cause it to fall onto the next shelf, where it has to be spread anew in a regular layer. Moreover, as the mass ofmaterial undergoing combustion at one timeis more considerable in the furnaces with perforated shelves, the materials are enabled to remain a longer time in the furnace, and the operation does not require to be so often repeated on the same materials. The cost of the labor, which is considerable in working pyrites-furnaces of this description as heretofore constructed, is thus materially diminished.

It is evident that the details of construction may be modified in various ways withoutdeparting from the spirit of the invention, which is not, limited to the particular form of construction illustrated in the accompanying drawings, which are merely given as examples of the best modes with which I am acquainted for carrying out the invention in practice. For example, I do not limit myself as to the number of shelves, the number, form, and arrangement of the perforations or openings a, the construction and thickness of the brick-work or walls M, its tight and heat-retaining envelope, or the number and arrangement of the working-holes C. The form of the front plate and the employment of a hot chamber, I), surrounding the sides, and other details are also optional, and can be varied or omitted according to circumstances andthe purposes-such as heating air, treating pyrites or other minerals, for example-to which the furnace maybe applied.

The furnace may, in fact, be employed for the combustion of any material capable of 4 being burned with the oxygen of the air. When it is used for treat-ing pyrites, (for producing sulphurous acid,) the latter is ground up into a powder or small pieces and is fed into the shelves in the manner above described with reference to the fuel.

I claim as my inventionl. A furnace for burning pulverulent materials, having shelves provided with perforations, whereby the combustible matter is caused to descend and arrange itself automatically in the form of a series of independent conical heaps arranged in such a manner that the gaseous agent supporting combustion is compelled to circulate around and impinge against the said heaps, all substantially as described.

2. A furnace provided with a series of perforated shelves for the fuel, the perforations in one shelf being opposite the solid parts in the next shelf, all substantially as described.

3. A furnace with perforated shelves placed nearer together at the lower than at the upper part of the furnace and presenting per- IOO mission of air, and passages for the circulation of the gases, substantially as and for the purpose described.

4. In a furnace, the shelves provided with 5 pelfomtions, in combination with :L projecting or raised part or bench, an ash-pit, openings, passages, and L brick-Work or other easing', substantially as described.

In testimony whereof I have signed my name to this speoiieaution in the presence ot' two 1o subscribing witnesses.

MICHEL PERRET.

Witnesses:

EUGNE MoUsTAYER,

EoRG. DERVIEUX. 

